Subamniotic haemorrhage is considered a type of perigestational haemorrhage.
Subamniotic haematomas are classical placental pathological lesions resulting from the rupture of chorionic vessels (allantochorionic vessels) close to the cord insertion.
A subamniotic hemorrhage is contained within amnion and chorion and thus extends anteriorly to placenta but is limited by reflection of amnion on placental insertion site of umbilical cord.
Most subamniotic haematomas are found after birth and result from excessive traction on the umbilical cord at delivery.
They may sonographically be detected as a solid mass (recent) or poorly reflective oval-shaped predominantly cystic mass (chronic), overlying the fetal plate of the placenta and covered in a thin membrane, adjacent to the cord insertion 4.
- placental cyst
- large umbilical cord cyst near the site of cord insertion
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